An INSTRUMENT is the "lowest" level of a sound in the Proteus, unlike the PRESET which is the "highest" level of a sound. An instrument is the basic building block of the preset, and consists of one or more samples or digital recordings of sounds. These samples are often organized as "multisamples" which means they are already assigned to the correct keys to make sure they play the correct note, and have already been looped and adjusted in volume so that they play correctly.